I am looking for a machine or tool that will form/curve metal. We
are making neck collars out of gold wire, [2mm to 5mm]. The plyers
that you can buy will curve metal into fairly nice curves but the
diameter is only about 1 1/2" with these plyers. these plyers also
tend to dent the wire because we are ateempting to use them for the
wrong size diameter. I need to have curves that are much larger, say
5" to 8" diameter size curves. There are things that do this for the
electrical industry to curve conduit but conduit is about 3/4"
tubing. Does anyone know where to get something to use with wire and
tubing that fits our specs?

What you need is a set of small Bending Rolls. They are widely used
by model engineers to curve sheet or rod to any radius down to the
size of the rolls themselves. They are comprised of 3 parallel rolls,
two geared together which grip and propel the workpiece forward,
whilst the 3rd deflects the workpiece to produce the curve. The
greater the deflection the tighter the curve. The following URL shows
the general idea.

say 5" to 8" diameter size curves. There are things that do this
for the electrical industry to curve conduit but conduit is about
3/4" tubing. Does anyone know where to get something to use with

I don’t know of a ready-made tool for that, but you could make a
circle of plywood to wrap around pretty easily. Put it on a base, put
some sort of clamp for the first end of wire - a screw-down piece of
metal would do it - and just wrap it around. If your wire is longer
than needed, it will give you leverage, and you won’t have to try to
get the very end rounded, in the large sizes. And it will tend to
spring back, but I’d think you could make a smaller circle with a
little experimentation so it springs back to just the size you want.
You could put some handle on an axle in the center, too, so when you
turned the handle it would wrap the wire around - pretty easy to do
but probably just doing it by hand would be easy enough.

is a small one (though I’ve never used this particular machine it
does look to be more suitable for small stuff than the 4’ one I have
used) You might need to be creative to handle your specific wire
sizes, or have extra grooves turned/ground into the rolls.

Do you have a hydraulic press? Bonny Doon makes mushroom formers
(daps) with 5", 6" and 8" curves (and smaller ones, too, of course).
I suggest that you use a master tool holder to hold the dap securely
to the top platen of the press, and push the wire into a 1" thick pad
of 95 durometer urethane to smoothly bend your neck wires.

Phil Poirier, who now makes all the Bonny Doon tools, has recently
posted a pdf of the Bonny Doon tool catalog on the Discussion Group
at www.bonnydoonengineering.com. Here’s a link:

Hi Dennis, A small slip roll is wonderful at curving metals of all
kinds. I use mine for hollowware and jewelry. Harbor Freight has a
small 12" slip roll that are perfect for what you are doing. You can
set the curve to a wide variety of diameters. This model is also
much cheaper and lighter than the ones used in machine shops. It
runs around $120.00, but you can catch it on sale now and then.